What are the Contact Pads underneath The Keyboards Called?

nathanm1991 · 23 June 2018, 23:58

Hi Peeps I have just tested My Spare A500 Keyboard Membrane with Tin Foil to Find it Is Completely Working, Turns out its the Contacts underneath the Keys on Certain Keys that I thought was The Membranes Fault. I need New ones but Can't find them On any Sale site but I think it is Because I Don't know the Actual Name for it.

Thanks to All

nathanm1991 · 24 June 2018, 00:07

as in the Rubber Feeling Contact Piece that Clips up into the Key

idrougge · 24 June 2018, 01:10

I think the name is "plunger", in this case Mitsumi KPR type or one of its siblings: https://deskthority.net/w/images/c/c..._datasheet.pdf

nathanm1991 · 26 June 2018, 03:10

Would there be anywhere I could buy these? Thanks

Jope · 26 June 2018, 09:21

If your only problem is shiny rubber contacts, you can take a piece of paper from your printer and use that to wipe at the rubbers until they are no longer shiny.

Clean any paper dust from the rubber contacts with compressed air or a q-tip soaked in isopropyl and reassemble. Also make sure your membrane is dust free. Don't use isopropyl on the membrane, only a paper towel dampened with plain water.

nathanm1991 · 26 June 2018, 11:42

will try this now and let you know

nathanm1991 · 26 June 2018, 12:17

Unfortunately I have had no luck reviving the Rubber Contacts. is there anywhere I can buy these new?

idrougge · 26 June 2018, 13:55

You can find a Compaq keyboard of a suitable age and steal its plungers.

nathanm1991 · 26 June 2018, 16:47

you guys are awesome. Compaq Presario Era OK for this?

idrougge · 26 June 2018, 17:54

Depends on the Presario, but just before Windows keys were introduced should be good.

nathanm1991 · 26 June 2018, 18:10

ace thanks :-)

nathanm1991 · 26 June 2018, 18:40

Could I use Conductive Paint to Repair these? as it is like using tin foil?

idrougge · 26 June 2018, 23:58

I wonder if not graphite paint would be better.

Jope · 27 June 2018, 09:06

You need to look under the keyboard to be sure. Look for the letters KPQ in the model number sticker under the keyboard.

Handy ebay search: https://www.ebay.de/sch/i.html?_nkw=mitsumi+kpq

I have never had the paper trick not work if the membrane / pcb under the key mechanism is working properly. Before spending money on a new keyboard, it's a good idea to measure the traces leading to the dead keys with a multimeter, also try swapping around the stems from other keys to see if the problem moves.

nathanm1991 · 27 June 2018, 12:40

Hi Jope I have Swapped a Few Stems over to see if this was Definitely the Case and it was as the Problem Moves to the Swapped Keys. I will Look at this Ebay thread now. Idrougge, I had the Exact Same thought and the Graphite should be here Friday but will still Definitely Replace if I Can

Jope · 27 June 2018, 13:35

I'd just keep wiping with the paper. :-) If the rubbers aren't split/cracked, you can rejuvenate them.

I would not use graphite.

nathanm1991 · 27 June 2018, 16:08

There is no splits or anything in the Rubbers. was trying for hours with the paper to no success but can keep trying.

Jope · 28 June 2018, 11:31

Hours? Should be done in a matter of minutes. Perhaps yours are indeed worn too low or something. The idea is to wipe only enough that they are dull again. In my experience that's like 10-20 wipes per rubber.

ajk · 28 June 2018, 11:35

@nathanm1991

How many failed ones have you got? I could probably find a few spares in my parts bin.

nathanm1991 · 28 June 2018, 14:47

I have 5 Failed Keys. Will pay you for them or if you need anything PC Wise I got thousands of Spares for Swaps, Just not much in the Amiga hardware side unfortunately as am a new collector. But if you have a Aros Machine I Have plenty of Spares :-)

23 June 2018, 23:58	#1
nathanm1991 Self Diagnosed Noob! Join Date: Apr 2018 Location: Malvern, Worcestershire Age: 32 Posts: 704	What are the Contact Pads underneath The Keyboards Called? Hi Peeps I have just tested My Spare A500 Keyboard Membrane with Tin Foil to Find it Is Completely Working, Turns out its the Contacts underneath the Keys on Certain Keys that I thought was The Membranes Fault. I need New ones but Can't find them On any Sale site but I think it is Because I Don't know the Actual Name for it. Thanks to All

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24 June 2018, 00:07	#2
nathanm1991 Self Diagnosed Noob! Join Date: Apr 2018 Location: Malvern, Worcestershire Age: 32 Posts: 704	as in the Rubber Feeling Contact Piece that Clips up into the Key

24 June 2018, 01:10	#3
idrougge Registered User Join Date: Sep 2007 Location: Stockholm Posts: 4,356	I think the name is "plunger", in this case Mitsumi KPR type or one of its siblings: https://deskthority.net/w/images/c/c..._datasheet.pdf

26 June 2018, 03:10	#4
nathanm1991 Self Diagnosed Noob! Join Date: Apr 2018 Location: Malvern, Worcestershire Age: 32 Posts: 704	Would there be anywhere I could buy these? Thanks

26 June 2018, 09:21	#5
Jope - Join Date: Jul 2003 Location: Helsinki / Finland Age: 43 Posts: 9,911	If your only problem is shiny rubber contacts, you can take a piece of paper from your printer and use that to wipe at the rubbers until they are no longer shiny. Clean any paper dust from the rubber contacts with compressed air or a q-tip soaked in isopropyl and reassemble. Also make sure your membrane is dust free. Don't use isopropyl on the membrane, only a paper towel dampened with plain water.

26 June 2018, 11:42	#6
nathanm1991 Self Diagnosed Noob! Join Date: Apr 2018 Location: Malvern, Worcestershire Age: 32 Posts: 704	will try this now and let you know

26 June 2018, 12:17	#7
nathanm1991 Self Diagnosed Noob! Join Date: Apr 2018 Location: Malvern, Worcestershire Age: 32 Posts: 704	Unfortunately I have had no luck reviving the Rubber Contacts. is there anywhere I can buy these new?

26 June 2018, 13:55	#8
idrougge Registered User Join Date: Sep 2007 Location: Stockholm Posts: 4,356	You can find a Compaq keyboard of a suitable age and steal its plungers.

26 June 2018, 16:47	#9
nathanm1991 Self Diagnosed Noob! Join Date: Apr 2018 Location: Malvern, Worcestershire Age: 32 Posts: 704	you guys are awesome. Compaq Presario Era OK for this?

26 June 2018, 17:54	#10
idrougge Registered User Join Date: Sep 2007 Location: Stockholm Posts: 4,356	Depends on the Presario, but just before Windows keys were introduced should be good.

26 June 2018, 18:10	#11
nathanm1991 Self Diagnosed Noob! Join Date: Apr 2018 Location: Malvern, Worcestershire Age: 32 Posts: 704	ace thanks :-)

26 June 2018, 18:40	#12
nathanm1991 Self Diagnosed Noob! Join Date: Apr 2018 Location: Malvern, Worcestershire Age: 32 Posts: 704	Could I use Conductive Paint to Repair these? as it is like using tin foil?

26 June 2018, 23:58	#13
idrougge Registered User Join Date: Sep 2007 Location: Stockholm Posts: 4,356	I wonder if not graphite paint would be better.

27 June 2018, 09:06	#14
Jope - Join Date: Jul 2003 Location: Helsinki / Finland Age: 43 Posts: 9,911	You need to look under the keyboard to be sure. Look for the letters KPQ in the model number sticker under the keyboard. Handy ebay search: https://www.ebay.de/sch/i.html?_nkw=mitsumi+kpq I have never had the paper trick not work if the membrane / pcb under the key mechanism is working properly. Before spending money on a new keyboard, it's a good idea to measure the traces leading to the dead keys with a multimeter, also try swapping around the stems from other keys to see if the problem moves.

27 June 2018, 12:40	#15
nathanm1991 Self Diagnosed Noob! Join Date: Apr 2018 Location: Malvern, Worcestershire Age: 32 Posts: 704	Hi Jope I have Swapped a Few Stems over to see if this was Definitely the Case and it was as the Problem Moves to the Swapped Keys. I will Look at this Ebay thread now. Idrougge, I had the Exact Same thought and the Graphite should be here Friday but will still Definitely Replace if I Can

27 June 2018, 13:35	#16
Jope - Join Date: Jul 2003 Location: Helsinki / Finland Age: 43 Posts: 9,911	I'd just keep wiping with the paper. :-) If the rubbers aren't split/cracked, you can rejuvenate them. I would not use graphite.

27 June 2018, 16:08	#17
nathanm1991 Self Diagnosed Noob! Join Date: Apr 2018 Location: Malvern, Worcestershire Age: 32 Posts: 704	There is no splits or anything in the Rubbers. was trying for hours with the paper to no success but can keep trying.

28 June 2018, 11:31	#18
Jope - Join Date: Jul 2003 Location: Helsinki / Finland Age: 43 Posts: 9,911	Hours? Should be done in a matter of minutes. Perhaps yours are indeed worn too low or something. The idea is to wipe only enough that they are dull again. In my experience that's like 10-20 wipes per rubber.

28 June 2018, 11:35	#19
ajk Registered User Join Date: May 2010 Location: Helsinki, Finland Posts: 1,341	@nathanm1991 How many failed ones have you got? I could probably find a few spares in my parts bin.

28 June 2018, 14:47	#20
nathanm1991 Self Diagnosed Noob! Join Date: Apr 2018 Location: Malvern, Worcestershire Age: 32 Posts: 704	I have 5 Failed Keys. Will pay you for them or if you need anything PC Wise I got thousands of Spares for Swaps, Just not much in the Amiga hardware side unfortunately as am a new collector. But if you have a Aros Machine I Have plenty of Spares :-)

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